This application claims the benefit of Japanese Application No. 2001-184678 filed Jun. 19, 2001.
The present invention relates to an ultrasonic imaging method and an ultrasonic imaging apparatus, and particularly to an ultrasonic imaging method and an ultrasonic imaging apparatus both for scanning the inside of an object with an ultrasonic beam on a sound-ray sequential basis and thereby receiving echoes, and generating a dynamic image, based on a Doppler signal of the echoes.
Upon ultrasonic imaging, the inside of an object is scanned with an ultrasonic beam on a sound-ray sequential basis to receive echoes. A tomogram is generated based on an echo""s intensity signal and displayed as a B-mode image. A dynamic image such as a blood flow or the like is generated using a Doppler signal of the echoes and displayed as a color Doppler image.
The degree of definition of an image varies according to a sound-ray density for scan. When the sound-ray density is made dense, the degree of definition thereof increases, whereas when the sound-ray density is made coarse, it is reduced. When a scan range is constant, a frame rate of an image is lowered when the sound-ray density is rendered dense, and the frame rate thereof is increased when the sound-ray density is rendered coarse. When the frame rate is constant, the scan range is narrowed when the sound-ray density is rendered dense, and the scan range is broadened when the sound-ray density is rendered coarse.
Since the above relationship is established between the sound-ray density, the scan range and the frame rate, it was difficult to enhance the degree of definition of an image without being affected by both the scan range and the frame rate. This particularly presents a problem upon such color Doppler imaging that a plurality of times of transmission and reception per sound ray are carried out.
Therefore, it is an object of the present invention to realize an ultrasonic imaging method and an ultrasonic imaging apparatus both capable of making both the maintenance of a scan range and a frame rate and high definition of an image compatible with each other.
(1) The invention according to one aspect for solving the problems is an ultrasonic imaging method for scanning the inside of an object with an ultrasonic beam on a sound-ray sequential basis and thereby receiving echoes, and generating a dynamic image, based on a Doppler signal of the echoes, characterized in that a sound-ray density for the scan is made to be nonuniform.
(2) The invention according to another aspect for solving the problems is an ultrasonic imaging apparatus for scanning the inside of an object with an ultrasonic beam on a sound-ray sequential basis and thereby receiving echoes, and generating a dynamic image, based on a Doppler signal of the echoes, characterized by being equipped with sound-ray density adjusting means for making a sound-ray density be nonuniform for the scan.
In the inventions according to the respective aspects described in (1) and (2), since the sound-ray density for the scan is made non-uniform, the sound-ray density of a required portion is rendered dense and other portions are rendered coarse, whereby the maintenance of a scan range and a frame rate and high definition of an image can be made compatible.
(3) The invention according to a further aspect for solving the problems is an ultrasonic imaging method for repeatedly scanning the inside of an object with an ultrasonic beam on a sound-ray sequential basis and thereby receiving echoes, and generating a dynamic image, based on a Doppler signal of the echoes, characterized in that a sound-ray density for the scan is made to be nonuniform while holding a range for the scan constant.
(4) The invention according to a still further aspect for solving the problems is an ultrasonic imaging apparatus for repeatedly scanning the inside of an object with an ultrasonic beam on a sound-ray sequential basis and thereby receiving echoes, and generating a dynamic image, based on a Doppler signal of the echoes, characterized by being equipped with sound-ray density adjusting means for making a sound-ray density be nonuniform for the scan while holding a range for the scan constant.
In the inventions according to the respective aspects described in (3) and (4), since the sound-ray density for the scan is made non-uniform while a scan range is being held constant, the sound-ray density of a required portion is rendered dense and other portions are made coarse, whereby the maintenance of the scan range and high definition of an image can be rendered compatible.
(5) The invention according to a still further aspect for solving the problems is an ultrasonic imaging method for repeatedly scanning the inside of an object with an ultrasonic beam on a sound-ray sequential basis and thereby receiving echoes, and generating a dynamic image frame, based on a Doppler signal of the echoes, characterized in that a sound-ray density for the scan is made to be nonuniform while holding a frame rate of the dynamic image frame constant.
(6) The invention according to a still further aspect for solving the problems is an ultrasonic imaging apparatus for repeatedly scanning the inside of an object with an ultrasonic beam on a sound-ray sequential basis and thereby receiving echoes, and generating a dynamic image frame, based on a Doppler signal of the echoes, characterized by being equipped with sound-ray density adjusting means for making a sound-ray density be nonuniform for the scan while holding a frame rate of the dynamic image frame constant.
In the inventions according to the respective aspects described in (5) and (6), since the sound-ray density for the scan is made nonuniform while the frame rate of the dynamic image frame is being held constant, the sound-ray density of a required portion is rendered dense and other portions are made coarse, whereby the maintenance of the frame rate and high definition of an image can be made compatible.
Preferably, the sound-ray density is rendered relatively dense at a bloodflow-existing portion and rendered relatively coarse at portions other than the portion in that a bloodflow image is brought into high definition.
The presence of the blood flow is preferably detected based on power of the Doppler signal in that the presence of the blood flow is reliably detected.
The presence of the blood flow is preferably detected based on a velocity determined from the Doppler signal in that the existence of the blood flow is reliably detected.
The presence of the blood flow is preferably detected based on a dispersion of the velocity obtained from the Doppler signal in that the presence of the blood flow is reliably detected.
The presence of the blood flow is preferably detected based on the velocity determined from the Doppler signal and the power of the Doppler signal in that the existence of the blood flow is detected more reliably.
The presence of the blood flow is preferably detected based on the dispersion of the velocity determined from the Doppler signal and the power of the Doppler signal in that the presence of the blood flow is detected more reliably.
The presence of the blood flow is preferably detected based on the velocity determined from the Doppler signal and its dispersion in that the presence of the blood flow is detected more reliably.
The presence of the blood flow is preferably detected based on the velocity determined from the Doppler signal and its dispersion, and the power of the Doppler signal in that the existence of the blood flow is detected still more reliably.
Preferably, the sound-ray density is rendered relatively dense at a portion specified by an external input and rendered relatively coarse at portions other than the portion in that the degree of freedom of a sound-ray density adjustment increases.
Therefore, an ultrasonic imaging method and an ultrasonic imaging apparatus each capable of making both the maintenance of a scan range and a frame rate, and high definition of an image compatible with each other can be realized.
Further objects and advantages of the present invention will be apparent from the following description of the preferred embodiments of the invention as illustrated in the accompanying drawings.